Water quality in the inshore Great Barrier Reef lagoon: Implications for long-term monitoring and management

Coastal and inshore areas of the Great Barrier Reef lagoon receive substantial amounts of material from adjacent developed catchments, which can affect the ecological integrity of coral reefs and other inshore ecosystems. A 5-year water quality monitoring dataset provides a 'base range' of water quality conditions for the inshore GBR lagoon and illustrates the considerable temporal and spatial variability in this system. Typical at many sites were high turbidity levels and elevated chlorophyll a and phosphorus concentrations, especially close to river mouths. Water quality variability was mainly driven by seasonal processes such as river floods and sporadic wind-driven resuspension as well as by regional differences such as land use. Extreme events, such as floods, caused large and sustained increases in water quality variables. Given the highly variable climate in the GBR region, long-term monitoring of marine water quality will be essential to detect future changes due to improved catchment management.     

东非裂谷坦噶尼喀湖的热液喷口

伴生有块状硫化物的湖底热液喷口是１９８７年４月在东非裂谷坦噶尼喀湖北部盆地靠扎伊尔一边的Ｐｅｍｂａ和Ｂａｎｚａ角发现的。一支由１０个配备有水下呼吸器的潜水员组成的多国（法国，扎伊尔，德国和布隆迪）ＴＡＮＧＡＮＹＤＲＯ探险队（１９９１年８～１０月），在坦噶尼喀湖西边界向北延伸的活动断层的４６ｍ水深处发现了热液喷口。测得热液流体和沉积物的温度为５３～１０３℃。在Ｐｅｍｂａ热液喷口附近，发现了厚１～１０ｃｍ的块状硫化物脉（黄铁矿和白铁矿条带）；而在Ｂａｎｚａ角，活动喷口却以１～７０ｃｍ高的霰石烟囱为特，在热液喷口脉壁外包有一层包晶黄铁矿层。这两个地区热液流体的端元组分明显不同。Ｐｅｒｎｂａ的端元组分富ＮａＨＣＯ＿３流体，类似于裂谷东支Ｍａｇａｄｉ和Ｂｏｇｏｒｉａ湖的ＮａＨＣＯ＿３热液流体。Ｂａｎｚａ角的端元组分却富ＮａＣｌ。这种卤水可能是深部基底成因的，类似于坦噶尼喀湖东侧的ＵｖｉｎｚａＮａＣｌ卤水。地热温标计算得到水—岩反应的温度在Ｐｅｍｂａ和Ｂａｎｚａ角各为２１９℃和１７９℃。围绕活动喷口发现有丰富的白色或红褐色微生物群，代表Ｂｅｇｇｉｎｔｏａ藻席。１３０℃处的右旋正断层与南北向主断裂交汇处的张裂隙有助于热液     

地面运动的平均周期对单自由度和多自由度体系的非弹性动力反应的影响

主要研究地面运动的频率成分在非弹性需求下对单自由度（SDF）和多自由度（MDF）钢架结构的作用。通过对文献进行详细的审查,识别出最能代表地面运动频率成分的指标。选择地面运动的平均周期（Tm）是由于它能区别各种不同地面运动的频谱形态及其与震级、距离和场地特征的关系。首先使用一组128次地面运动的记录根据L对单自由度体系在特定延性水平时的非弹性位移要求进行研究。然后通过采用相同的地面运动资料做增量动力分析,把研究扩展到多自由度系统,评价Tm对各种工程需求参数的影响。得到的结果表明,对于单自由度体系,当弹性周期（Te）与Tm的比值低于1时,位移将增大。对于多自由度体系,结果证明了高阶振型对于基底剪力的影响和当Tm接近结构的高阶振型周期时,对最大层间侧移的影响变得更加显著。对单自由度体系和多自由度体系,在非弹性水平较高时这些观测更为明显。研究结果对于欧洲抗震设计法是尤为重要的。     

Hepatic biomarkers of sediment-associated pollution in juvenile turbot, Scophthalmus maximus L

Hatchery-reared turbot (Scophthalmus maximus L.) were exposed for 3 weeks, under laboratory conditions, to sediment collected from polluted sites in Cork Harbour and a reference site at Ballymacoda, Co. Cork, Ireland. The potential of surficial sediment for inducing hepatic biomarkers was assessed at two levels of biological organisation: expression of cytochrome P450 [Western blotting analysis and 7-ethoxy-resorufin O-dealkylase (EROD), 7-benzoxy resorufin O-dealkylase (BROD), 7-methoxy resorufin O-dealkylase (MROD), 7-pentoxy-resorufin O-dealkylase (PROD) activities] and DNA integrity (Comet assay). Positive controls were generated, either by exposing turbot to cadmium chloride-spiked seawater (Comet assay) or to beta-naphthaflavone by intraperitoneal injection (cytochrome P450 induction). The induction of cytochrome P450 activity (EROD, MROD and PROD) in animals following a 7-day exposure to contaminated sediments was significantly higher than those exposed to reference site sediment and remained elevated thereafter; BROD was not induced. DNA single-strand breaks were also significantly higher following exposure to contaminated sediments throughout the experiment. Although no direct correlation between induction of alkoxyresorufin O-dealkylase activities and a particular chemical class was established, the induction of MROD and PROD activities in fish exposed to sediments containing complex contaminant mixtures, appeared to be more sensitive than conventional EROD activity assays. We conclude from the present laboratory study that S. maximus is a suitable sentinel species for the assessment of moderately contaminated sediments and therefore allows for the further development of this model for future, ecologically relevant, field studies.     

Expression of superoxide dismutase (SOD) genes from the copper-exposed polychaete, Neanthes succinea

To evaluate the superoxide dismutase (SOD) genes as a potential indicator of environmental stress, we cloned and sequenced the full-length cDNA of a Cu/Zn-SOD and Mn-SOD genes from the marine polychaete, Neanthes succinea. Ns-Cu/Zn- and Mn-SOD expression was measured using quantitative real-time RT-PCR in response to the oxidative stress induced by copper in the form of CuCl2. Ns-Cu/Zn-SOD expression increased in a dose dependent manner but the increase of Mn-SOD expression was evident only at a high concentration of copper. Particularly, Ns-Mn-SOD dramatically increased in the 72 μg/L CuCl2-exposed groups, indicating that both Ns-SOD genes were induced by copper exposure. These results suggest that Ns-Cu/Zn- and Ns-Mn-SOD would play important roles in the detoxification of cellular oxidative stresses in the polychaete, N. succinea. Furthermore, as part of field work, the marine polychaete, N. succineaCu/Zn-SOD mRNA collected from the polluted area was accordingly upregulated in expression but not for NS-Mn-SOD.     

致密砂岩衰减岩石物理图板分析:储层微裂隙预测

致密砂岩储层普遍具有孔隙度低、微裂隙发育的特点,岩石内部常含有强烈的结构非均质性.致密砂岩发育的微裂隙使储层具有良好的连通性,促成高饱和气的天然气成藏.针对川西某探区须家河组高含气饱和度致密砂岩,本文选取致密砂岩岩心样本,进行了不同围压下的超声波实验测量.考虑储层完全饱气情况下的粒间孔隙、微裂隙双重孔隙结构,采用Biot-Rayleigh双重孔隙方程,构建致密砂岩岩石物理模型,进而分析了裂隙含量对纵波频散和衰减的影响.基于地震波衰减,构建了致密砂岩多尺度岩石物理图板.采用谱比法和改进频移法估算致密砂岩样本及储层衰减,对超声和地震频带下的图板进行校正.将校正后的图板应用到研究工区,选取二维测线和三维区块,进行储层孔隙度和裂隙含量的定量预测.对比实际资料进行分析,结果显示,本文预测的孔隙度和裂隙含量与三口测井的孔隙度曲线和实际产气情况基本吻合,基于孔隙-裂隙衰减岩石物理模型有效地预测了优质储层的分布区域.     

Magma chamber growth models in the upper crust: A review of the hydraulic and inertial constraints

Finite volumes of magma moving in confinement, store hydraulic potential energy for the generation,control and transmission of power. The Pascal's principle in a hydraulic jack arrangement is used to model the vertical and lateral growth of sills. The small input piston of the hydraulic jack is equivalent to the feeder dike, the upper large expansible piston equivalent to the magmatic chamber and the inertial force of the magma in the dike is the input force. This arrangement is particularly relevant to the case of sills expanding with blunt tips, for which rapid fracture propagation is inhibited. Hydraulic models concur with experimental data that show that lateral expansion of magma into a sill is promoted when the vertical ascent of magma through a feeder dike reaches the bottom contact with an overlying, flat rigid-layer. At this point, the magma is forced to decelerate, triggering a pressure wave through the conduit caused by the continued ascent of magma further down(fluid-hammer effect). This pressure wave can provide overpressure enough to trigger the initial hydraulic lateral expansion of magma into an incipient sill, and still have enough input inertial force left to continue feeding the hydraulic system. The lateral expansion underneath the strong impeding layer, causes an area increase and thus, further hydraulic amplification of the input inertial force on the sides and roof of the incipient sill, triggering further expansion in a self-reinforcing process. Initially, the lateral pressure increase is larger than that in the roof allowing the sill to expand. However, expansion eventually increases the total integrated force on the roof allowing its uplift into either a laccolith, if the roof preserves continuity, or into a piston bounded by a circular set of fractures. Hydraulic models for shallow magmatic chambers, also suggest that laccolith-like intrusions require the existence of a self-supported chamber roof. In contrast, if the roof of magmatic chambers loses the self-supporting capacity, lopoliths and calderas should be expected for more or less dense magmas, respectively, owing to the growing influence of the density contrast between the host rock and the magma.